Following the rapid advance of electronic and information technologies, all kinds of electronic products (such as desktop computers and notebook computers) have been more and more popularly used and widely applied to various fields. There is a trend to miniaturize the sizes and thin the thickness of the electronic products. As exemplified with a notebook computer, the thickness of the notebook computer is thinner and thinner. Consequently, due to limitation of the space, the heat generated by the electronic components inside the notebook computer, such as the central processing unit (CPU), can be hardly efficiently dissipated. In this case, the heat will accumulate to cause a rise of temperature.
In order to avoid temporary or permanent failure of the notebook computer due to overheating of the CPU, conventionally, a thin-type fan is directly disposed on the CPU to forcedly quickly dissipate the heat generated by the CPU to external environment so as to keep the CPU normally working at high speed.
Please refer to FIGS. 1A and 1B, in which FIG. 1A is a perspective exploded view of a conventional fan housing structure, while FIG. 1B is perspective assembled view of the conventional fan housing structure. The fan housing structure is made of plastic material, including a base seat 10 and an upper cover 13. The base seat 10 has a bush 101 and multiple perforations (not shown) around the bush 101. The bush 101 is formed at a center of the base seat 10 for mating with a corresponding fan propeller 14. The base seat 10 has a sidewall 12 perpendicularly extending from a periphery of the base seat 10. The sidewall 12 and the base seat 10 together define a space 15 in communication with the perforations. Two opposite ends of the sidewall 12 define therebetween a wind exit 151 in communication with the space 15. The upper cover 13 has an opening 131 in communication with the space 15. The upper cover 13 is fitted on the base seat 10 to form the fan housing structure.
The conventional base seat 10, bush 101 and sidewall 12 are made by means of integral injection molding. The bush 101 integrally protrudes from the base seat 10. As a result, the axial thickness of the base seat 10 is increased. This leads to insufficient room of the fan housing structure. Moreover, in the injection molding process of the conventional fan housing structure, the base seat 10 must have sufficient thickness. For example, in the case that the base seat 10 simply has a thickness of 0.5 mm, the base seat 10 is apt to deform and damage. Under such circumstance, the fan housing structure will apparently have poor structural strength, especially in the base seat 10. According to the above, the conventional fan housing structure has the following defects:    1. The conventional fan housing structure is apt to deform.    2. The conventional fan housing structure has insufficient room.    3. The conventional fan housing structure has poor strength.